Beneficial roles of feed additives as immunostimulants in aquaculture: a review

Seafood is a growing part of the economy, but its economic value is dimin- ished by marine diseases. Infectious diseases are common in the ocean, and here we tabulate 67 examples that can reduce commercial species' growth and survivorship or decrease seafood quality. These impacts seem most problem- atic in the stressful and crowded conditions of aquaculture, which increas- ingly dominates seafood production as wild fishery production plateaus. For instance, marine diseases of farmed oysters, shrimp, abalone, and various fishes, particularly Atlantic salmon, cost billions of dollars each year. In comparison, it is often difficult to accurately estimate disease impacts on wild populations, especially those of pelagic and subtidal species. Farmed species often receive infectious diseases from wild species and can, in turn, export infectious agents to wild species. However, the impact of disease ex- port on wild fisheries is controversial because there are few quantitative data demonstrating that wild species near farms suffer more from infectious dis- eases than those in other areas. The movement of exotic infectious agents to new areas continues to be the greatest concern.

Infectious Diseases Affect Marine Fisheries and Aquaculture Economics

Historic emergence, impact and current status of shrimp pathogens in Asia

Parasites of North American Freshwater Fishes

The rise of aquaculture has been one of the most profound changes in global food production of the past 100 years. Driven by population growth, rising demand for seafood and a levelling of production from capture fisheries, the practice of farming aquatic animals has expanded rapidly to become a major global industry. Aquaculture is now integral to the economies of many countries. It has provided employment and been a major driver of socio-economic development in poor rural and coastal communities, particularly in Asia, and has relieved pressure on the sustainability of the natural harvest from our rivers, lakes and oceans. However, the rapid growth of aquaculture has also been the source of anthropogenic change on a massive scale. Aquatic animals have been displaced from their natural environment, cultured in high density, exposed to environmental stress, provided artificial or unnatural feeds, and a prolific global trade has developed in both live aquatic animals and their products. At the same time, over-exploitation of fisheries and anthropogenic stress on aquatic ecosystems has placed pressure on wild fish populations. Not surprisingly, the consequence has been the emergence and spread of an increasing array of new diseases. This review examines the rise and characteristics of aquaculture, the major viral pathogens of fish and shrimp and their impacts, and the particular characteristics of disease emergence in an aquatic, rather than terrestrial, context. It also considers the potential for future disease emergence in aquatic animals as aquaculture continues to expand and faces the challenges presented by climate change.

/pdf/emerging-viral-diseases-of-fish-and-shrimp-21djjo4r9g.pdf

Emerging viral diseases of fish and shrimp

Shrimp is one of the main aquaculture species in the world. Different viruses affect them, which causes serious mortality to economically important species, such as Penaeus monodon, Litopenaeus vannamei and L. stylirostris, among others. White spot syndrome virus or WSSV is a highly lethal, stress-dependent virus, which belongs to the family Nimaviridae, genus Whispovirus. Three WSSV virus isolates were first detected in 1992 in Thailand, Taiwan and China. Later, a fourth isolate of the virus was detected in the Americas in 1999. This virus has a large circular double-stranded DNA genome with different sizes (292.9-307.2 kb), where the diverse isolates show differences in virulence. This virus infects a wide range of aquatic crustaceans by vertical and horizontal transmission, with different mortality results. The spread of infection between regions may be due to infected shrimp and carriers such as other crustaceans, seabirds, aquatic arthropods or other vectors. The aim of this work is to describe the current knowledge on the status, transmission, pathology, isolation, control and genomic characteristics of WSSV.

White Spot Syndrome Virus in cultured shrimp: A review

Research on an innate immune system of penaeid shrimp is greatly motivated by economical requirements, because their culture is limited by the development of infectious diseases. As invertebrates, shrimp’s natural immunity acts as a fast and efficient defence mechanism against the pathogens. Their immune system involve hemocytes (for encapsulation, nodule formation and phagocytosis), several plasma components (antimicrobial peptides, histones, lysosomal enzymes, lipopolysaccharide, β-1,3-glucan binding proteins, and recognition molecules), and multimeric systems (clotting protein cascade, prophenoloxidase system). When these defense mechanisms fail to protect the shrimp against bacteria, viruses, fungi, protozoa and their products, disease develops and a negative impact takes place in the shrimp culture system. Studying the shrimp immune system is attractive for the advancement of a basic knowledge on invertebrate and vertebrate general immunity, because it offers various possible alternatives for disease management in shrimp aquaculture. The aim of this document is to present the general status of the shrimp defense system, to help in the development of strategies that favour the control and prevention of disease.

/pdf/penaeid-shrimp-immune-system-23of931lgy.pdf

Penaeid Shrimp Immune System

Pathogenicity and Infection Route of Vibrio parahaemolyticus in American White Shrimp, Litopenaeus vannamei

The prophylactic use of potassium permanganate (KMnO4) and oxytetracycline and its effects on catfish growth were assessed. For eleven weeks, healthy channel catfish, Ictalurus punctatus, juveniles were exposed to KMnO4 and oxytetracycline. KMnO4-treated fish were exposed to 1 ppm twice a week for 1 h, while oxytetracycline-treated fish received a 50 mg/kg dose in the feed (35 fish per tank, two tanks per treatment). Assessed parameters included body weight and length, specific growth rate (SGR), feed intake (FI), condition, and feed conversion index (FCI). Potassium permanganate did not have a suppressive effect on growth, while oxytetracycline significantly enhanced growth on channel catfish (weight and length), as they were heavier (12.5%) than KMnO4-treated fish and controls at the end of the trial. SGR (%/d), FI, and FCI were not significantly different (P > 0.05) among the three groups of fish. Condition index (K) was significantly higher (ANOVA, P < 0.05) in the oxytetracycline-treated fish. The present study suggests that, at concentrations commonly used in aquaculture, exposure of healthy channel catfish to oxytetracycline enhanced growth, while KMnO4 does not induce growth suppression.

A Preliminary Study on the Effects on Growth, Condition, and Feeding Indexes in Channel Catfish, Ictalurus punctatus, after the Prophylactic Use of Potassium Permanganate and Oxytetracycline

The production of aquatic organisms for human consumption has been decreasing while its demand has increased. The decline of fish products from fisheries has been in part compensated by the aquaculture industry. The need for enhanced disease resistance, feed efficiency, growth performance and lower production costs of cultured organisms is substantial for various sectors of this industry. Different products have been used at some extent to prevent disease and as growth promoters; however, their inadequate application can create adverse disorders, environmental imbalances, and increase predisposition to disease. In the search of new disease control and prevention options, several studies have been carried out to test some functional additives (probiotics). Probiotics have been shown to improve energy expenditure derived from sources such as carbohydrates and increase the incorporation of protein for growth; and to increase the immunity and disease resistance of the host. The use of probiotics in aquaculture has high potential application at a commercial level; however, it has been poorly characterized and studied. This study aims to review the use and action of probiotics in the culture of aquatic organisms (bivalve, fish, shrimp); and the potential for further application of this in aquaculture production.

Gabriel Aguirre-Guzmán

Papers

White Spot Syndrome Virus in cultured shrimp: A review

Penaeid Shrimp Immune System

Pathogenicity and Infection Route of Vibrio parahaemolyticus in American White Shrimp, Litopenaeus vannamei

A Preliminary Study on the Effects on Growth, Condition, and Feeding Indexes in Channel Catfish, Ictalurus punctatus, after the Prophylactic Use of Potassium Permanganate and Oxytetracycline

The use of probiotics in aquatic organisms: A review